Preparation Of Carbon-Supported Highly Dispersed Non-Noble Metal Catalysts And Their Applications In Oxygen Reduction

With the increasing consumption of fossil energy,the environmental pollution issue is increasingly serious.Therefore,it is urgent to develop new energy conversion devices.However,the cathode oxygen reduction reaction process of fuel cell is slow and requires noble metal Pt-based catalyst catalysis.The low reserves of precious metal catalysts,high prices,poor cycle stability and other shortcomings limit the large-scale commercial application of fuel cells.Therefore,the development of highly efficient and stable non-precious metal catalysts to promote the large-scale commercialization of fuel cells and other devices has become a general trend.In this paper,a series of highly dispersed carbon-supported non-noble metal oxygen reduction catalysts were prepared.By adjusting the heteroatom doping and the morphology of the catalysts,the catalytic activity of the electrocatalysts for oxygen reduction reaction was investigated.1.Phenolic resin porous microspheres were prepared by Stboer derivatization with resorcinol and formaldehyde as monomer through phenolic condensation reaction.The electrocatalyst Fe-NC with rich active sites(Fe-Nx)was obtained by pyrolysis in ammonia gas,which was used for electrocatalytic oxygen reduction.After carbonization,phenolic resin microspheres maintained their original morphology and had larger specific surface area,which was beneficial to the adsorption of O2 in the reaction process.The catalyst showed excellent electrochemical performance and good cycle stability in alkaline solution.Half-wave potential is 0.839 V,higher than commercial Pt/C 31 mV.Moreover,the material had excellent methanol resistance,and was a good candidate material for methanol fuel cell electrocatalyst.2.With ultra-thin lamellar g-C3N4 as template and polyethyleneimine as ligand,Co-PEI-900 with high dispersion of carbon-supported metal Co was prepared by one-step pyrolysis.The influence of pyrolysis temperatures of the electrocatalyst on the oxidation reduction reaction was investigated.The catalyst had a two-dimensional ultra-thin graphene morphology structure,and the research showed that the structure was beneficial to the transport of substances and electrons.The half-wave potential in alkaline electrolyte was 0.865 V,which was superior to commercial Pt/C and had the same limit current density as Pt/C.Co-PEI-900 electrocatalyst had excellent tolerance to methanol and good stability.This work provided a new design idea for the design of energy storage conversion electrocatalysts.This method will play an important role in developing fuel cell electrocatalysts with high efficiency and low cost.3.We have prepared Co-NC-900 electrocatalyst by a sacrificial template method,with g-C3N4 was used as a two-dimensional(2D)template.The high dispersion of Co was realized by introducing zinc and ligand,which can protect the nanoparticles from agglomerate during the pyrolysis process.because of the folded layer structure and high dispersion of Co nanoparticles,the Co-NC-900 electrocatalyst exhibits excellent electrocatalytic performance for ORR in alkaline solution,and its half-wave potential was 0.838 V,which was better than Pt/C(0.808 V vs RHE).The zinc-air battery assembled with Co-NC-900 as air cathode material had a high-power density of 160 mW cm-2,and can still maintain stability after 45 h of the charge-discharge cycle,which proved that its excellent charge-discharge cycle stability was superior to that of commercial Pt/C electrocatalyst.This work not only provides a simple and low-cost way to prepared layered porous materials but also opened a new way to improve the electrocatalytic performance of non-noble metal materials.